Motor-control system



A. A. GAZDA.-

MOTOR CONTROL SYSTEM.

APPLICATION HLED'SEPT. 30. 15MB.

All.

WITNESSES Patented May 3, 1921.

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UNITED STATES PATENT OFFICE.

ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOR-CONTROL SYSTEM.

Specification o f Letters Patent.

Patented May 3,. 1921.

Application filed September 30, 1516. Serial No. 123,067.

To all whom it may concern..-

Be it known that I, AnoLPH A. GAZDA, a citizen of the United States, anda resident of lVilkinsbur in the county of Allegheny and State ofennsylvania, have invented a new and useful Improvement in Motor-Control Systems, of which the following is a specification.

My invention relates-to motor-control systems and it has particularrelation to such systems as are employed in connection with printingpresses and similar machines.

My invention has for its object to provide a simple and effective meanswhereby machines operated by electric power may be driven slowly at auniform speed.

In the operation of printing presses, it is necessary that they bestarted slowly and gradually in order to avoid tearing the paper in therolls and disturbing the adjustment of the several parts. It isdesirable, also, to operate the press at a low speed during thepreliminary work of making up or preparing for regular operation at fullspeed. It is essential that the press be operated at a uniform speedduring the process of making up. It is practically impossible to securesatisfactory performance if the main driving motor is employed to drivethe press during such operation because the motor is operated at anunstable point in its characteristic curve.

According to the present invention, I provide a main motor and anauxiliary motor which are arranged to be operatively connected fordriving the press at a relatively low speed. The motors are connected byreduction gear mechanism so arranged that, when the main motor operatesat a low speed, the auxiliary motor rotates at substantially its normalfull speed. The armatures of the motors are connected in series and thevalue of the current traversing the armature of the main motor iscontrolled by the counter-electromotive force of the auxiliary motorwhen the main motor tends to operate above a predetermined speed. The

operative connection of the motors is broken when the circuit of themain motor is adjusted to operate the latter at its higher speeds.

The details of my invention will be described in connection with theaccompanying drawing in which the single figure is a diagrammatic viewof circuits and apparatus embodying my invention.

Line conductors 1 and 2 supply energy to a main motor, the armature ofwhich is indicated at 3 and which may be operatively connected in anysuitable manner to a printing press or other mechanism (not shown). Themain motor is provided with a shunt field-magnet winding 4.

An auxiliary motor, having an armature 5 and a shunt field-magnetwinding 6, is adapted to be operatively connected to the main motor byreduction-gear mechanism 7 and a friction clutch 8. The clutch 8 iscontrolled by a solenoid 9 and a spring 10.

The circuits of the motors are controlled by an electromagnetic switch11 and a controller 12. The controller comprises an armatureresistor 13anda field resistor 14 which are respectively connected in series withthe armature winding 3 and the field magnet winding 1 of the main'motor.The resistors are controlled by a movable arm 15 that is actuated by apilot motor 16. The pilot motor is provided with field-magnet windings17 and 18 which are respectively energized for operating the motor 16and arm 15 in'opposite directions.

The operation of the pilot motor is controlled by means of push-buttonswitches 19, 20, 21 and 22, two sets or stations of which are shown byway of example. The several push buttons are designated by appropriatelegends which indicate the respective effects produced upon theoperation of the system by their actuation.

' It may be assumed that the motors are stationary and that the arm 15occupies its inoperative position, which is at the end of its path ofmovement in a clockwise direction. The clutch 8 is engaged to connectthe armatures of the motors 3 and 5.

When a line switch 24 is closed, a circuit is completed which extendsfrom line conductor 2 through switch 24, controller arm 15, contactmember 25, actuating coil 26 and switch 24 to line conductor 1. The coil26 is energized to actuate a no-voltage relay 27 to its upper position.The closing of the no-voltage relay 27 operates to complete a controlcircuit for the several push buttons whereby the latter are renderedeffective to govern the operation of the motors.

When the controller arm is in its off position, the motors may beoperated for any,

desired length of time to drive the press at a minimum speed by closingthat one of the push-button switches 21 which is designated Inch. Theclosing of the push-button switch completes a circuit which extends fromno-voltage relay 27, which is connected to line conductor 2, through thepushbutton switches 22 and 21, contact member 28, insulated contactmember 29 on the controller arm, contact segment 30 and actuating coil31 of switch 11 to line conductor 1.

The switch 11 then closes to connect the armature of the main andauxiliary motors in series with a resistor 32.

The main motor 3 operates-at a relatively low speed while the auxiliarymotor 5 rotates at a comparatively high speed by reason of the fact thatthey are connected through the reduction-gear mechanism 7. The motorsmay be stopped at any deslred time by releasing the push button 21 andthereby opening the circuit of the C011 31 of the switch 11. Thearmature circuit of the motors are thereupon opened by switch 11. WVhenit is desired to operate the driven mechanism slowly and uniformly, apush button 19, which is designated Increase, is actuated to complete acircuit for the pilot motor 16. This circuit extends from the novoltagerelay 27 through switches 22 and 19, conductor 32, limit switch 33,field-magnet winding 17, and armature 16, to line conductor 1. T hepilot motor 16 then actuates the controller arm 15 in acounter-clockwise direction.

When the insulated contact member 29 engages a contact segment 34, theactuating coil 31 is again energized by a circuit which extends fromno-voltage relay 27 through switches 22, contact segment 34, contactmember 29, contact segment 30 and coil 31 to line conductor 1.

If the push button 19 be released while the arm 15 occupies a positionto maintain the circuit just described, the motors will continue torotate uniformly, the main motor and the mechanism to which it may beconnected being operated at a low speed. An increase in the speed of themain motor 3 causes a much greater increase in the speed of theauxiliary motor 5 relative to its normal speed and the increasedelectromotive force of the latter causes a decrease in the value of thecurrent traversing the armature circuits of the motors and acorresponding decrease in their speeds. The auxiliary motor thusperforms the function of a governor to maintain the operation of thesystem at a substantially constant speed.

When the preliminary operation of making up has been completed, the pushbutton 19 is again actuated to complete the circuit of the pilot motor,as above traced, and the controller arm 15 is again actuated in acounter-clockwise direction. When the insulated contact member 29,engages a contact segment 35, a circuit is completed which extends fromthe contact segment 34, which is connected tothe line conductor 2, asabove traced, through contact member 29, contact segment 35 and coil 36to line conductor 1. The coil 36 is energized to close a switch 37 whichconnects the solenoid coil 9 in series with the armature of the mainmotor and the resisto 13.

The coil 9 is energized to disengage the clutch 8 against the tension ofthe spring 10. The motors are thus disconnected mechanically, and themechanism is driven by the main motor alone. At substantially the sametime that the contact member 29 engages the contactsegment 35, it isseparated from the contact segment 30 to open the circuit of theactuating coil 31 of switch 11. The latter then opens to break thecircuit of the auxiliary motor 5.

The operator may hold the push-button switch 19 in its closed positionuntil the controller arm 15' has efiectedthe increase in speed of themotor 3 to the desired rate by removing the resistance 13 from thearmature circuit and inserting a portion or all of the resistor 14 incircuit with the fieldmagnet winding 4. The motor 3 then rotates at itsnormal speed to actuate the press during its regular operation.

Vhen it is desired to decrease the speed of the motor, a push-buttonswitch 20 which is designated Decrease, is actuated to complete acircuit for the pilot motor which extends from no-voltage relay 27through the switches 22 and 20, limit switch 38, fieldmagnet winding 18and armature 16 to line conductor 1. The pilot motor 16 is thus reversedto actuate the arm 15 in a clockwise direction to remove the resistor 14from the field circuit of the motor. The push but ton 20 will bereleased by the operator when the speed of the motor has been reduced tthe desired rate.

To stop the motor at any time, it is only necessary to actuate a pushbutton 22, whereupon the coil 26 of no-voltage relay 27 and coil 36 ofswitch 37 are deenergized. The no-voltage relay 27 then falls to itslower position, and switch 37 opens to break the circuit of the mainmotor and the coil 9. The spring 10 effects the engagement of the clutch8 in preparation for the succeeding starting operation.

When the no-Voltage' relay 27 is in its lower position, whether throughthe actuation of the stop button or because of a failure of voltage, themotors cannot be operated until the controller arm 15 again occupies itsinoperative position. Upon the return of line voltage or the closing ofline switch 24, a. circuit for the pilot motor is completed whichextends from line conduc- Limit switches 33 and 38 operate to limit 7the movement of the controller arm 15 in the respective directions. Itwill be noted that the limit switches 33 and 38 are respectively inseries with the field-magnet windings 17 and 18. When one of the limitswitches is open, the circuit of the pilot motor 16 can be completedonly through that field-magnet winding which causes it to rotate insuch'direetion as to return the controller arm to an intermediateposition.

It will be noted that I provide a simple arrangement whereby a drivenmechanism may be started slowly and gradually or may be operateduniformly at low speeds. The starting operation can occur only when thecontrolling mechanism is in its inoperative position.

I claim as my invention:

1. In a control system, the combination with a plurality of electricmotors, of a switch for operatively connecting them tooperate at apredetermined speed, and controlling means for successively effectingthe operative connection of said motors, the operation of one of saidmotors at a relatively low speed, the disconnection of said motorsmechanically and electrically and the operation of said one motor at arelatively high speed.

2. The combination with a pair of electric motors and a controllertherefor for successively effecting the operation of one of said motorsat a relatively low speed, the disconnection of said motors and theoperation of said one motor at a relatively high speed, of means foroperatively connecting said motors when said controller occupies aninoperative position. i

3. In a control system, the combination with a plurality of electricmotors and mechanical means for operatively connecting them, of meansfor connecting the armature windings of said motors in series relationand for controlling said mechanical means whereby the motors aredisconnected when one of them is arranged to operate above apredetermined speed.

4. In a control system, the combination with a pair of electric motors,and means comprising reduction-gear mechanism for operatively connectingthem, of means comprising a coil in series with one of said motors forcontrolling said connecting means, means comprising an electromagneticswitch for electrically connecting said motors in series relation, andmeans for controlling the circuit of said coil and the operation of saidswitch.

5. In a control system, the combination with a main motor and anauxiliary motor, and reduction-gear mechanism and a clutch foroperatively connecting them, of a coil in series with the main motor forcontrolling said clutch, a switch for controlling the connection ofsaidmotors in series relation, and controlling means for said coil andsaid switch for successivelyetfecting the connec tion of said motors ata relatively low speed, the disconnection of said motors, bothelectrically and mechanically, and the acceleration of said main motor.

with a main motor and an auxiliary motor, and reduction-gear mechanismand a clutch for operatively connecting them, of a coil in series withthe main motor for controlling said clutch, a switch for controlling theconnection of said motors in series relation, and means for successivelyeffectin the closing of said switch, the opening of said switch and theacceleration of said main motor.

7. In a control system the combination with a plurality of electricmotors and means for operatively connecting them, of controlling meansfor said motors comprising a controller, a pilot motor for actuatingsaidcontroller; means for causing said pilot motor to effect the connectionof said'motors for series operation and for effecting the connection ofsaid motors in series independently of said pilot motor.

8. In a control system,'the combination with a plurality of electricmotors, of controlling means therefor comprising a movable contactmember, a pilot motor for actuating said contact member, anelectromagnetic switch for connecting said motors in series relation,and means for causing said pilot motor to effect the closing of saidswitch and for closing said switch inclependently of said pilot motor.

9. In a control system, the combination with a plurality of electricmotors and an electromagnetic switch for electrically connecting saidmotors, of a power-actuated member for controlling said switch, andmanually operable means for controlling said member and for effectingthe closing of said switch either through the actuation of 80 6. In acontrol system, the combination with an electric motor and'a controllertherefor having a movable arm, of a pilot motor for actuating said arm,a plurallty of manually operable switches for controlling the operationof said pilot motor and for effecting a slow rotation of said motorindependently of said pilot motor,and means for rendering said switchesinoperative upon a failure of voltage until said arm occupies itsinoperative position.

12. The combination with a plurality of electric motors normallymechanically connected together, of means for operatively electricallyconnecting the same, and means for successively effecting the operationof said motors, the disconnection of said motors mechanically andelectrically, and the continued operation of one of said motors.

13. The combination with a pair of electric motors,- a controller foreffecting the starting and the stopping of said motors, means foractuating said controller, of a manually operable switch for effectingthe connection of said motors to cause them to operate independently ofsaid actuating means.

In testimony whereof, I have hereunto subscribed my name this 26th dayof Sept, 1916.

ADOLPH A. GAZDA.

